A time certifying server has a clock unit that outputs time information. Units of time equal to or larger than a predetermined unit are acquired from the time information. Units of time from the time information smaller than the predetermined unit are corrected using an acquired correction time and without correcting the acquired units of time equal to or larger than the predetermined unit. A reference time is received from a reference time distributing server that distributes reference time. A verification process is then executed to verify that the clock unit operates at a precision falling within a predetermined range by confirming that, in the time of the units equal to or larger than the predetermined unit, the acquired time and the received reference time coincide with each other. A certification target information that serves as time certification target is received from a client terminal. Time certification information of the received certification target information is generated after verification of the operational precision of the clock unit using the corrected units of time. The generated time certification information is transmitted to the client terminal.